I do not believe Mint is a true rolling release. Most Ubuntu-based distributions are "semi-rolling releases", for lack of a better term. Most of them have a "new release" every quarter year. There are few true rolling release distros. It probably has something to do with the latest software often, or usually?, having bugs. If Mint does not have the latest version, you will probably need to endure the hardship of waiting for a few weeks.

If you are going to try it I would also recommend you make a note of the ppa name and also install the package ppa-purge. That way, if the upgrade makes something go pear-shaped you can reverse out of it.